The Government last year gave the smelter's owner, New Zealand Alumunium Smelters, $30 million in an effort to keep it operating until at least 2017. Transpower said it is in constant discussion with Tiwai Point's owners, because if the smelter does close, Transpower would need to upgrade its grid.
Its former chief executive Patrick Strange said the smelter's owners have told Transpower they plan on keeping the smelter running for the long-term.
Dr Strange said a 90 million dollar upgrade project would be triggered if Tiwai announced it was shutting down.
"We've done all the engineering work, we've got all the consents, we're ready to go, but we would not spend the money until the day we know that Tiwai is definitely going to go."